Fuel compositions for vehicles are continually being improved to enhance various properties of the fuels in order to accommodate their use in newer, more advanced engines including direct injection gasoline engines. Accordingly, fuel compositions typically include additives that are directed to certain properties that require improvement. For example, friction modifiers are added to fuel to reduce friction and wear in the fuel delivery systems and piston rings of an engine. In addition, special components may be added to fuel to reduce injector nozzle fouling, clean dirty injectors and improve the performance of direct injection combustion engines. When such additives are added to the fuel, a portion of the additives is transferred into the thin film of lubricant in the engine piston ring zone where it may also reduce friction and wear and thus improve fuel economy. Such fuel additives are passed into the crankcase during engine operation, so that a fuel additive that is also beneficial to the engine lubricant is desirable. However, fuel additive concentrates containing friction modifiers made from diethanolamine and certain fatty acids or their corresponding esters, may be unstable when stored at low temperatures and the performance of such friction modifiers is often less than desirable. In addition, certain fatty acid based amine and alkanolamide friction modifiers are waxes or partial solids that are difficult to handle at low ambient temperatures.
Friction modifiers that are made from acids and esters that are derived from saturated or mono-unsaturated fatty acids such as lauric, myristic, palmitic, and stearic acid are particularly difficult to formulate into additive concentrates that remain fluid and homogeneous at low temperatures. The instability can be exacerbated by the typical detergent additives that are used in fuel additive concentrates, such as polyisobutene Mannich additives. Since additive concentrates are the preferred form to blend fuel additive components into the fuel, it is essential that fuel additive concentrates be homogeneous and remain fluid at low temperatures, preferably down to about −20° C. or lower.
When the friction modifier additive concentration is fairly high in the concentrate, compatibilizers and/or large amounts of solvent may be added to the additive composition to improve its solubility at low temperatures. Compatibilizers that have been used include low molecular weight alcohols, esters, anhydrides, succinimides, glycol ethers, and alkylated phenols, and mixtures thereof. Alternatively, some additive producers have incorporated low molecular weight esters into the reaction mixture of fatty acids with the diethanolamine to enhance the low temperature stability of the reaction product. Unfortunately, the costs that solvents, compatibilizers, and low molecular weight esters add to additive concentrates may make their use uneconomical.
Partial esters of fatty acids and polyhydroxy alcohols such as glycerol monooleate (GMO) and fatty amine ethoxylates such as diethoxylated laurylamine are also known fuel additives that reduce friction and wear and may improve fuel economy. GMO and some fatty amine ethoxylates have poor compatibility in fuel additive concentrates when the concentrates are stored at low temperatures. It is particularly difficult to prepare fuel additive concentrates containing both GMO and fatty amine diethoxylates that are stable at low temperature. While GMO and fatty amine ethoxylate friction modifiers may improve fuel economy when added to a fuel, GMO and certain fatty amine ethoxylates may be unstable in additive concentrates or may require large amounts of solvent and compatibilizers to keep the additive concentrate stable and fluid at low temperatures. Accordingly, GMO, fatty amine ethoxylates, and fatty alkanolamide friction modifiers cannot be beneficially added to a fuel composition to improve the fuel economy and wear protection of the fuel delivery system unless they can be formulated into a stable fuel additive concentrate.
Many other friction modifiers have been tried, however there remains a need for a friction modifier that can be readily formulated into fuel additive concentrates that are stable at low temperatures, i.e., temperatures as low as about −20° C. There is also a need for a friction modifier that improves the low temperature compatibility of other fuel additive components in fuel additive concentrates. Moreover, there is a need for a friction modifier that improves the friction and wear properties of other fuel additives. Additionally, there is a need for a friction modifier that improves fuel economy, and that provides wear protection to fuel delivery systems, among others characteristics.
Fuel compositions for direct fuel injected engines often produce undesirable deposits in the injectors, engine combustion chambers, fuel supply systems, fuel filters, and intake valves. Accordingly, improved compositions that can prevent deposit build up and maintain cleanliness “as new” for the life of the vehicle are desired. A composition that can clean dirty fuel injectors, restore performance to the previous “as new” condition and improve the power performance of the engines is desirable and valuable for reducing air borne exhaust emissions. Although there are additives known to reduce injector nozzle fouling and reduce intake valve deposits, their clean-up performance and keep clean effect may be insufficient. Furthermore, their stability and interaction with other fuel additives may be unsatisfactory. Accordingly, there continues to be a need for a fuel additive that is cost effective, readily incorporated into additive concentrates, and improves multiple characteristics of a fuel.
In accordance with the disclosure, exemplary embodiments provide a fuel additive concentrate for gasoline, a gasoline fuel containing an additive mixture, a method for reducing wear in an engine and in a fuel delivery system of a gasoline engine, and a method for improving injector performance. The additive concentrate includes an aromatic solvent and a mixture that contains (i) N,N-bis(2-hydroxyethyl)alkylamide, (ii) 2-((2-(bis(2-hydroxyethyl)amino)ethyl)-amino)ethyl alkanoate and N-(2-(bis(2-hydroxyethyl) amino)ethyl)-N-(2-hydroxyethyl)alkyl-amide, and (iii) fatty acid ester(s) and amide(s) derived from a self-condensation product of diethanolamine (DEA) containing at least 3 amino groups. A weight ratio of (i) to (ii) to (iii) in the concentrate ranges from about 8:2:0 to about 2:5:3. The fuel additive mixture is substantially devoid of glycerin and remains fluid at a temperature down to about −20° C.
In one embodiment there is provided a gasoline fuel composition for reducing fuel system component wear and engine friction, and improving injector cleanliness. The composition includes A) gasoline and B) a fuel additive mixture that contains a) N,N-bis(2-hydroxy-ethyl)alkyl amide, b) 2-((2-(bis(2-hydroxyethyl)amino)ethyl)amino)ethyl alkanoate and N-(2-(bis(2-hydroxyethyl)-amino)ethyl)-N-(2-hydroxyethyl)alkylamide, and c) fatty acid ester(s) and amide(s) derived from a self-condensation product of diethanolamine (DEA) containing at least 3 amino groups, wherein the alkyl groups of the amide(s) and ester(s) contain from 8 to 18 carbon atoms. A weight ratio of (a) to (b) to (c) in the fuel additive mixture ranges from about 8:2:0 to about 2:5:3. The fuel additive mixture is substantially devoid of glycerin and remains fluid at a temperature down to about −20 C°.
In accordance with another embodiment of the disclosure, there is provided a method for reducing wear and engine friction. The method includes providing gasoline containing a wear reducing additive mixture that consists essentially of: a) N,N-bis(2-hydroxy-ethyl)alkyl amide, b) 2-((2-(bis(2-hydroxyethyl)amino)ethyl)amino)ethyl alkanoate and N-(2-(bis(2-hydroxyethyl)amino)ethyl)-N-(2-hydroxyethyl)alkylamide, and c) fatty acid ester(s) and amide(s) derived from a self-condensation product of diethanolamine (DEA) containing at least 3 amino groups. The additive mixture is substantially devoid of glycerin and a weight ratio of (a) to (b) to (c) ranges from about 8:2:0 to about 2:5:3. The additive mixture is combined with gasoline to provide a fuel composition and the engine is operated on the fuel composition.
A further embodiment of the disclosure provides a method for improving the injector performance of a fuel injected gasoline engine. The method includes providing gasoline containing an injector cleaning additive mixture that consists essentially of: a) N,N-bis(2-hydroxy-ethyl)alkyl amide, b) 2-((2-(bis(2-hydroxyethyl)amino)ethyl)amino)ethyl alkanoate and N-(2-(bis(2-hydroxyethyl)amino)ethyl)-N-(2-hydroxyethyl)alkylamide, and c) fatty acid ester(s) and amide(s) derived from a self-condensation product of diethanolamine (DEA) containing at least 3 amino groups. The additive mixture is substantially devoid of glycerin and a weight ratio of (a) to (b) to (c) ranges from about 8:2:0 to about 2:5:3. The additive mixture is combined with gasoline to provide a fuel composition and the engine is operated on the fuel composition.
In some embodiments, the additive mixture contains less than 3 wt. % diesters and diamides that are derived from the reaction of a second fatty acid with the aforementioned alkanolamides and esters and amides and esters derived from self-condensation products of DEA.
In some embodiments, the additive mixture contains less than 3 wt. % N,N′-bis(2-hydroxyethyl)piperazine, such as less than 0.5 wt. % N,N′-bis(2-hydroxyethyl)piperazine based on a total weight of the additive mixture.
In some embodiments, the additive mixture contains from about 5 to about 30 wt. % of fatty acid ester(s) and amide(s) derived from a self-condensation product of DEA containing at least 3 amino groups based on a total weight of the additive mixture.
In other embodiments, the alkyl groups of the amide(s) and ester(s) contain from 8 to 18 carbon atoms. In some embodiments, 45 to 55 wt. % of the alkyl groups in the amide(s) and ester(s) are dodecyl groups.
In some embodiments, an additive concentrate for gasoline contains from about 10 to about 90 wt. % of the fuel additive mixture described above based on a total weight of the additive concentrate.
In other embodiments, the fuel additive concentrate also contains one or more detergents and one or more carrier fluids.
In some embodiments, fuel additive concentrate further includes a friction modifier selected from partial esters of fatty acid and polyhydroxy alcohols, N,N-bis(2-hydroxyalkyl)-alkylamines, and mixtures thereof, wherein a weight ratio of friction modifier to fuel additive mixture in the concentrate ranges from about 10:1 to about 1:10
In some embodiments, a gasoline containing the fuel additive mixture described above has a high frequency reciprocating rig (HFRR) wear scar of no more than about 690 μm.
In some embodiments, a gasoline containing the fuel additive mixture described above has injector clean-up improvement of 98%.
In a further embodiment, the fuel composition contains from about 10 to about 1500 ppm by weight, such as from about 40 to about 750 ppm by weight, or from about 50 to about 500 ppm by weight, or from about 50 to about 300 ppm by weight of the fuel additive mixture.
As set forth above, the additive mixture as described herein surprisingly and quite unexpectedly is a stable fuel additive mixture that remains liquid at low temperature and also provides an improvement in friction and wear reduction of a fuel composition containing the additive mixture. It was also surprising and quite unexpected that the additive mixture as described herein was effective in cleaning dirty fuel injectors sufficient to provide improved engine performance. The additive mixture also provides suitable friction and wear reduction that is at least as good, if not better than the friction and wear reduction provided by conventional friction modifiers.
Additional embodiments and advantages of the disclosure will be set forth in part in the detailed description which follows, and/or can be learned by practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.